sparse: demonstrate a bug when used with safe-share stable

sparse: demonstrate a bug when used with safe-share

sparse: lock the store when updating requirements config

Differential Revision: https://phab.mercurial-scm.org/D11766

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tests/test-sparse-with-safe-share.t	Tue Nov 16 17:35:57 2021 +0000
@@ -0,0 +1,25 @@
+Same with share-safe
+
+  $ echo "[format]"         >> $HGRCPATH
+  $ echo "use-share-safe = True" >> $HGRCPATH
+
+  $ cd $TESTTMP
+
+  $ hg init myrepo
+  $ cd myrepo
+  $ cat > .hg/hgrc <<EOF
+  > [extensions]
+  > sparse=
+  > EOF
+
+  $ echo a > show
+  $ echo x > hide
+  $ hg ci -Aqm 'initial'
+
+Verify basic --include
+
+  $ hg up -q 0
+  $ hg debugsparse --include 'hide'
+  devel-warn: write with no lock: "requires" at: *mercurial/scmutil.py:1558 (writerequires) (glob)
+
+TODO: bug in sparse when used together with safe-share^